# Comsol Analysis

by Peaceman185
Tags: analysis, comsol
 P: 12 Hi, as I said, I tried to start it all over, changing the parameters I wasn't so sure last week but I don't see any difference. I'm pretty sure my problem is on the contact parameters definition but I don't know where to go with this. I changed the CAD to keep only the blade I'm interested in. I want to force the roller to follow a specific helix that I have the equation : Rx = R*cos(theta) Ry = R*sin(theta) Rz = R1*theta^9+R2*theta^8+...+R10*theta^0 (or should it be (R1*theta^9+R2*theta^8+...+R10*theta^0)*theta because the Z parameter of an helix = c*theta where c is a constant) It doesn't matter if it rotate on himself or no. In my mind, this path is only for a specific point (because of the Rz equation), this is why I constrained the subdomain with Rx and Ry and "the" point with Rz. To simplify, I'm trying to solve it without friction. The contact pressure is very low; I try to simulate the movement and the contact before augmenting it. Does everything seem to be OK for you? Do I have to set special initial values?
 PF Patron Sci Advisor P: 1,098 Contact problems and convergence often seem to reside on different planets. If the mesh is "about ok" one of the best ways to accelerate convergence would be to specify an initial contact pressure. Either find something analytical which would match approximately, or then just try to approximate based on the contact problem characteristic dimensions & loading (and improve by iteration for example, or if pressure seems out of the question, a following displacement at the beginning aids as well). Also, trying to simplify the problem if it doesn't converge is one which often works (add constraints, simplify them, then work towards getting to model to work with in the actual analysis case) and pay attention to effects and specification of load stepping.